1. Technical Field
The present invention relates to a roll paper supply device that unrolls and supplies roll paper, and to a printing device that has the roll paper supply device.
2. Related Art
Receipt printers and other types of printers that print on roll paper are commonly used in POS (point-of-sale) systems, for example.
Japanese Unexamined Patent Appl. Pub. JP-A-2009-102129, for example, teaches a roll paper printer having a roll paper supply mechanism that, when seen from the end of the center axis of the roll paper stored in the roll paper compartment, pulls the recording paper from a position (D) on one side of a vertical line (V) passing through the center of gravity of the roll paper stored in the roll paper compartment, has supply rollers positioned on the other side of this line, and has an urging surface of an urging member positioned between this vertical (V) and the pull-off position (D) of the recording paper.
With this roll paper supply mechanism the force of pulling the recording paper, the weight of the paper roll, and the conveyance force of the supply rollers produce a moment in the direction preventing the paper roll from lifting up, and the recording paper is thus held in contact with the supply rollers.
However, with a drop-in loading type of roll paper compartment such as taught in JP-A-2009-102129, that is, a roll paper compartment in which the roll paper rests on its side in the roll paper compartment instead of being supported at the axis of rotation of the paper roll, when the outside diameter of the paper roll becomes small, the roll paper starts rolling along the urging surface and may separate from the urging surface such that stable side pressure is not applied. When this happens the paper roll may start bouncing around inside the roll paper compartment when the recording paper is pulled off and supplied to the transportation path, resulting in the roll paper not being supplied smoothly and possibly becoming skewed.
In addition, instead of simply dropping the paper roll into the roll paper compartment when loading a small diameter paper roll into the roll paper compartment, the paper roll must be positioned to the urging position of the urging surface in order to ensure sufficient side pressure on the paper roll, and this complicates paper loading.